Many families (particularly owners of above-the-ground pools) are not home during the day and need to swim at night or, even if they are at home, find it too hot to swim during the day. It is dangerous, however, to swim at night in a swimming pool without underwater lights. Lights from above are effective at illuminating the pool side but make the water look black. If a swimmer gets into trouble, it may be difficult to find him in the dark, particularly at the deep end of the pool.
Accidents and panic situations may arise in a variety of ways. For example, children who cannot swim like to jump into the deep end of a pool wearing a "floatie". If the floatie breaks or if the child falls off or is pushed off, it may be necessary to rescue him. There are many other ways for a mishap to occur. For example, a person may dive into the water and hit the bottom in the dark or miss the deep water drop off and suddenly find himself in over his head and so forth.
Underwater lights are sold for in-the-ground pools and above-the-ground pools but are more common in the case of in-the-ground pools. For both types, however, commercially available underwater lights are relatively expensive and are designed to be installed through the sidewall of the pool. Unless they are installed when the pool is built, the installation requires that the pool be drained. In addition, particularly with above-the-ground pools, there is a substantial chance that water will leak through the sidewall around the light.
Because of the expense, many pools (in-the-ground and above-the-ground) do not have underwater lights, notwithstanding the need for them.
A solution to the above-mentioned problem came about by accident, quite literally, when the applicant broke the glass envelope (which is very fragile) of an underwater halogen fishing light sold by the Brinkmann Corporation under U.S. Pat. No. 4,947,304. The applicant replaced the envelope with a tube from a rain gauge and installed a plexiglass tube around it to prevent breakage. In testing the device for water tightness, discovered that the light illuminated his swimming pool. The cord for the light, however, was a safety hazard to swimmers and the light drew copious numbers of bugs (the purpose for which it designed as a fishing light).